Abstract

All-solid photonic crystal fibers (PCFs) are created by pressure-assisted filling of low-melting-point chalcogenide and tellurite glasses into silica matrix fibers with channel diameters as small as 200~nm. Overcoming to a large extent the problem of viscosity and, thus, process incompatibility of silica and non-silicate optical glasses, the technique provides a unique way of producing waveguiding devices with high core-cladding index-contrast, high optical non-linearity and a transmission range that extends into the mid infrared. In this paper, as a prerequisite for waveguide production, the rheologic properties and controlled flow of highly-viscous liquids under geometrically confined conditions are considered, and deviations from Newtonian behavior are discussed. Because the filling process requires only very small quantities of filling material that do not come into contact with the environment, and because ultra-high cooling rates can be achieved, the technique enables the use of difficult-to-handle or reactive optical glasses.